GB1051959A - - Google Patents

Abstract

1,051,959. Automatic position control. G.E. LONG and H. G. ANSON. May 28, 1965, No. 22738/65. Heading G3R. [Also in Division E1] In a travelling machine having two independently movable portions, one is maintained at a desired height by automatic control and the other is automatically controlled to maintain a constant slope of means connecting the two portions. As applied to an automatic paving machine, Fig. 1, (not shown), asphalt issuing from an opening 3 at the rear of a vehicle is smoothed and levelled by a screed 14 having an adjustable angle of attack and supported by arms 7 and 8 which are adjustable vertically by electric or hydraulic reversible motors 12 and 13 on each side of the vehicle. A cross-beam 23 coupling arms 7 and 8 carries a pulley 21, or skid type feeler, to detect the height of screed 14 relative to a guide wire 24, or previously laid surface, respectively. The feeler actuates a two-way drum switch controlling, through relays, the motor, e.g. 12, associated with one arm, e.g. 8, so that one side of the layer of asphalt is maintained at a level defined by the wire or previously laid surface despite any irregularities in the ground over which the vehicle is travelling. If desired, lateral deviations of the feeler may be arranged to steer the vehicle to maintain its course parallel to the wire automatically. Cross-beam 23 also carries a two-way switch unit 88 operated by a damped pendulum detecting changes in the transverse inclination of screed 14. The pendulum, which is gimballed. to counteract the effect of longitudinal tilt, controls, through the two-way switch unit and further relays, the motor, e.g. 13, associated with the other arm, e. g. 7, to maintain the transverse inclination of the asphalt at a value determined by adjustments to the switch unit. The sensitivity of the switch unit may be varied by adjusting the position of its contacts or introducing resistance-capacity networks. When it is desired to progressively vary transverse slope as the vehicle travels along, e.g. to produce a banked curve, a rotary switch driven with the vehicle produces a number of pulses, dependent on the distance travelled, which, starting from one value of the slope, actuate uni-selector switches preset to pass a predetermined proportion of the pulses to one or other of two stepping motors adjusting the datum of the pendulum switch unit progressively until the desired new slope is produced at the required distance. Constructional details of the detectors, which may incorporate indicator lamps, is given.